It has been proposed in U.S. Pat. No. 6,568,426 (to which WO99/63225 corresponds) to provide a manually operated timer switch, which is pressed each time the user of a caravan, for example, wishes to operate a tap. In this way irritating intermittent operation of the water pump is avoided, for example brought about by very low volume leaks. However, the abovementioned prior art arrangement suffers from the significant disadvantage that automatic equipment such as a washing machine or dishwasher cannot be allowed to operate automatically. Instead, manual intervention is required on each occasion where the washing machine or dishwasher requires a fresh load of water. Similarly self monitoring flow valve applications triggered by a demand for water, cannot function with this prior art arrangement. It is not known by the applicant whether this prior art arrangement has ever been used commercially.
U.S. Pat. No. 5,064,347 discloses a system for preventing water loss from a pump supply system which operates from a water well. Whether the pump is above ground or submerged in the well itself, when the pump of this system is de-energized, it is not possible for water to flow upwardly out of the well and through the non-operative pump. Thus de-energizing the pump stops the flow of water from the well.
However, in the case of a source of harvested water such as a rain water tank, or a dam, which is always above ground level, de-energizing the pump does not necessarily stop the flow because water can still flow by either gravity flow, or by means of a syphon, from the tank or dam through the de-energized pump.